In general, a rotation apparatus, generally referred to as a spin head, is employed for forming the panel surface film of a cathode ray tube. A plan view of the rotation apparatus is shown in FIG. 1A, and a front view thereof is shown in FIG. 1B. As shown in FIGS. 1A and 1B, the rotation apparatus comprises: a discoid faceplate 2 for holding the periphery of the panel of a cathode ray tube 1 fitted therein in such a manner that the cathode ray tube 1 is directed downward; and a plurality of support rollers (e.g., four rollers) 3a, 3b, 3c and 3d arranged at regular intervals around the faceplate 2. The faceplate 2 is rotatably supported by the support rollers 3a, 3b, 3c and 3d. A rotating roller 4, which is coupled to a driving motor 6 through a gear mechanism 5, is in contact with the outer circumference of the faceplate 2. The faceplate 2 is rotated at high speed by means of the gear mechanism 5 and the rotating roller 4 when the driving motor 6 is actuated.
In this type of rotation apparatus, however, the support rollers 3a, 3b, 3d and 3d and the driving roller 4 are in contact with the outer circumference of the faceplate 2. In addition, the driving roller 4 is coupled to the driving motor 6 through the gear mechanism 5. Therefore, when the faceplate 2 is rotated at high speed, the rotation apparatus makes a loud noise. In the case of a panel surface film formation apparatus comprising dozen or so rotation apparatuses, the level of the noise made will be as high as 96 phons, and a solution to this problem is thus desired.
Since the support rollers 3a, 3b, 3c and 3d and the driving roller 4 are kept in contact with the outer circumference of the faceplate 2, they may be abraded very much due to the rotation, and may become eccentric. In addition, since dust is caused by the abrasion, maintenance is troublesome.
As described above, the conventional rotation apparatus, wherein the faceplate is supported by means of support rollers that are in contact with the outer circumference of the faceplate and is rotated by the driving roller that are also in contact with that outer circumference, has problems in terms of the high-level noise it makes, the eccentricity due to abrasion, the generation of dust, etc.
The present invention has been made in consideration of the above circumstances, and one object of the invention is to provide a torque transmission apparatus which suppresses the noise and abrasion and is of a simple structure.
Another object of the present invention is to provide an apparatus adapted for forming a panel surface film of a cathode ray tube and employing a torque transmission apparatus which suppresses the noise and abrasion and is of a simple structure.
A still another object of the present invention is to provide an apparatus adapted for forming a panel surface film of a cathode ray tube and employing a plurality of torque transmission apparatuses each of which suppresses the noise and abrasion and is of a simple structure.